Targeting innate immune pathways in breast cancers with chromosomal instability

项目概要/摘要 虽然在治疗原发性乳腺癌方面取得了相当大的进展，但转移性乳腺癌仍然存在 主要是一个挑战。转移性乳腺癌细胞通常具有染色体不稳定性（CIN），涉及 染色体水平的改变导致基因组拷贝数异常。目标定位的重大挑战 CIN 驱动的乳腺癌是由于缺乏已知的可靶向改变。我们最近发现 CIN 亲 微粒癌细胞中的慢性炎症信号传导。当染色体错误分离时，它们常常会变得不正常。 包裹在微核中。随后的微核破裂使基因组双链 DNA 暴露于 细胞质。胞浆 DNA 激活抗病毒先天免疫途径，其中主要是 cGAS-STING 信号 - ing。正常情况下，cGAS-STING 激活可促进 I 型干扰素并促进细胞- 介导的免疫。 STING 与正常上皮细胞的结合会诱导衰老和细胞死亡。我们 然而，已经表明癌细胞凭借其自身特性对 cGAS-STING 激活具有内在抵抗力。 长期暴露于胞质 DNA。相反，它们上调 STING 下游的替代途径，例如 作为 NF-κB 信号传导。癌细胞依赖慢性炎症信号传导的程度尚不清楚。 明白了。更重要的是，它们如何破坏先天免疫信号以避免免疫监视仍然存在 未知。我们正在进行的工作表明，cGAS-STING 信号传导被隔离在癌细胞中，远离 主机。此外，人类乳腺肿瘤会上调 ENPP1（cGAS-STING 信号传导的负调节因子）。 ENPP1 通过降解 cGAMP（cGAS 产生的第二信使）来实现免疫逃避，仅在 细胞外空间。因此，ENPP1 可以阻止宿主 STING 响应肿瘤至宿主 cGAMP 的激活 转移。引人注目的是，STING 的药理学抑制可抑制黑色素同基因模型中的转移。 癌症、乳腺癌和结肠癌。我们假设这是因为它对肿瘤细胞的抑制作用超过了它的保护作用 主机中的角色。在这项工作的基础上，我们将扩大对乳腺癌 STING 抑制的临床前测试。 cer 探索其延迟转移和治疗耐药性的功效（目标 1）。然后我们将检查 cGAMP 是否有助于通过元-抑制免疫微环境的形成 细胞外空间的代谢分解（目标 2）。最后，我们将开发基于 cGAS-STING 的生物标志物 前瞻性收集肿瘤标本。我们将测试cGAS-STING信号的状态和 ENPP1 水平可以预测对新辅助化疗和 atezolizumab（一种免疫治疗药物）的反应 最近被批准用于治疗转移性乳腺癌（目标 3）。我们的工作解决了临床上未满足的问题 需要针对具有 CIN 的乳腺癌子集，并且治疗选择有限。如果 成功将为 STING 抑制剂治疗的首次人体测试提供临床前依据 癌症转移以及开发新型 CIN 相关生物标志物来预测治疗反应。

PROJECT SUMMARY/ABSTRACT While considerable progress has been made in treating primary breast cancers, metastatic breast cancers re- main a challenge. Metastatic breast cancer cells typically have chromosomal instability (CIN) that involves chromosome-level alterations leading to genomic copy number abnormalities. A major challenge in targeting breast cancers driven by CIN is the lack of known targetable alterations. We recently found that CIN pro- motes chronic inflammatory signaling in cancer cells. As chromosomes missegregate, they often become en- capsulated in micronuclei. Subsequent micronuclear rupture exposes genomic double-stranded DNA to the cytosol. Cytosolic DNA activates anti-viral innate immune pathways, chief among which is cGAS-STING signal- ing. Under normal circumstances, cGAS-STING activation promotes type I interferon and facilitates cell- mediated immunity. Engagement of STING in normal epithelial cells induces senescence and cell death. We have shown that cancer cells, however, are intrinsically resistant to cGAS-STING activation by virtue of their chronic exposure to cytosolic DNA. Instead, they upregulate alternative pathways downstream of STING, such as NF-κB signaling. The extent to which cancer cells depend on chronic inflammatory signaling is poorly un- derstood. More importantly, how they subvert innate immune signaling to avoid immune surveillance remains unknown. Our ongoing work reveals that cGAS-STING signaling is sequestered in cancer cells away from the host. Furthermore, human breast tumors upregulate ENPP1, a negative regulator of cGAS-STING signaling. ENPP1 enables immune evasion by degrading cGAMP, the second messenger produced by cGAS, only in the extracellular space. As such ENPP1 prevents host STING activation in response to tumor-to-host cGAMP transfer. Strikingly, pharmacologic inhibition of STING suppresses metastasis in syngeneic models of melano- ma, breast, and colon cancers. We postulate this is because its inhibition in tumor cells outweighs its protective role in the host. Building on this work, we will expand our pre-clinical testing of STING inhibition in breast can- cer probing its efficacy in delaying metastasis and therapeutic resistance (Aim 1). We will then examine whether cGAMP contributes toward the formation of an immune suppressive microenvironment through meta- bolic breakdown in the extracellular space (Aim 2). Finally, we will develop cGAS-STING-based biomarkers in prospectively collected tumor specimens. We will test whether the status of cGAS-STING signaling and ENPP1 levels can predict response to neoadjuvant chemotherapy and atezolizumab, an immunotherapeutic recently approved for the treatment of metastatic breast cancer (Aim 3). Our work addresses a clinically unmet need by targeting a subset of breast cancers with CIN and for which there are limited therapeutic options. If successful it will provide pre-clinical rationale for first-in-human testing of STING inhibitors for the treatment of cancer metastasis as well as the development of novel CIN-related biomarkers to predict therapeutic response.